These studies will continue the development of mycoplasma virology. Areas to be examined are: (1) analysis of events in the integration of mycoplasmavirus L2 DNA into the cell chromosome in persistently infected cells; (2) biochemical details of the restriction and modification of mycoplasmavirus L2; (3) investigation of the factors affecting mycoplasmavirus L2 morphological heterogeneity; and (4) biochemistry of cell membrane virus receptors.